Local number portability (LNP), as defined in the Telecommunications Act of 1996, is “the ability of users of telecommunications services to retain, at the same location, existing telecommunications numbers without impairment of quality, reliability, or convenience when switching from one telecommunications carrier to another”.
With the convergence of landline and mobile (cellular) telecommunications networks, the management of call routing between landline and cellular infrastructures, referred to as “mobility management”, presents a challenge to carriers.
Traditionally, landline networks and mobile networks have been operated by separate companies resulting in disparate operations across the networks. Landline switches perform LNP analysis to determine whether a landline-originated call needs to be routed to a mobile network. If yes, then the call is routed to a gateway mobile switching center (GMSC). The GMSC then queries a mobility management database (e.g., a home location register (HLR)), which maintains the identity of a visited MSC (V-MSC) to which the mobile subscriber is currently attached. The database (e.g., the HLR) then queries the V-MSC to obtain a temporary routing number, called a mobile subscriber routing number (MSRN), for that particular call. Thereafter, the MSRN number is returned to the GMSC, the GMSC then routes the call to that MSRN, and the V-MSC associates the incoming call to the MSRN with the destination mobile subscriber.
A similar technique is typically used for mobile-originated calls to a destination mobile subscriber. The originating MSC performs LNP analysis and then routes the call to the GMSC, which GMSC performs the HLR interrogation and receives an MSRN so that the GMSC can complete the call to the V-MSC. This design results in the landline switching network and the originating MSCs having one or more direct connections (called trunk groups) to the GMSC to transport the calls to the GMSC.
In the reverse scenario for mobile-originated calls to landline destinations, the originating MSC performs LNP analysis and determines that the destination number is on the landline network. Since landline phone connections are permanently affixed to a particular landline switch, there is no need for mobility management analysis to determine the current switch serving the destination landline number. Thus, the originating MSC typically has a direct trunk group to the landline switching network, because it would be inefficient, costly, and unnecessary to route the call through the GMSC.
As landline and wireless telecommunications networks converge into one company, there are inefficiencies with the traditional approach. The traditional approach requires multiple trunk groups from the landline network to the GMSC, landline network to originating MSCs, and originating MSCs to GMSCs. These multiple trunk groups are expensive from a transport and switching perspective. Further, the inability of the landline network to perform any mobility management analysis requires the continued expenditure of capital on GMSC equipment.
The landline switches utilize the traditional signaling protocols to support LNP analysis and intelligent network (IN) services. However, landline switches do not support the mobile application part (MAP) signaling protocols necessary to query the HLR, and thus, to support mobility management. It can be very expensive and time-consuming to facilitate an upgrade the traditional landline switches to support MAP signaling. Further, it is inefficient from a capital expenditure perspective to upgrade these switches given the pending evolution to voice over IP (VoIP) soft switches.
Additionally, conventional mobility management attempts do not support the CAMEL (customized application for mobile enhanced logic) signaling protocol that is utilized between GMSCs and service control points (SCPs) to provide specialized mobility services such as prepaid cellular service, personalized audible ringing service, and other special services that require signaling interaction for mobile-terminated calls. Moreover, conventional mobility management attempts do not provide the traditional GMSC call detail record (CDR) that is oftentimes required by IT (information technology) billing systems either as the primary billing record or as used in reconciling with V-MSC CDR before it is used as the primary billing record. Accordingly, alternative and more effective means for performing mobility management and analysis are desirable.